wissam sabbah - Profile on Academia.edu (original) (raw)

Papers by wissam sabbah

Research paper thumbnail of Evaluation of silver-sintering die attach

Silver sintering die attach is a promising technology for high temperature power electronics pack... more Silver sintering die attach is a promising technology for high temperature power electronics packaging. In this paper, we evaluate its performances in terms of thermal resistance and high temperature stability. The thermal resistance is measured on test vehicles assembled under different conditions, using silver pastes from NBETech and Heraeus, with different process parameters. The stability test is performed by storing samples at an elevated temperature (300°C) in air, with a strong voltage bias (1100 V) for several hours.

Research paper thumbnail of Study of die attach technologies for high temperature power electronics: Silver sintering and gold–germanium alloy

Microelectronics Reliability, 2013

Silver sintering joints and AuGe soldering are promising technologies for high temperature (>200°... more Silver sintering joints and AuGe soldering are promising technologies for high temperature (>200°C ambient) power electronics packaging. This paper presents the implementation of two silver-sintering processes with the one hand micrometer-scale silver particles, and on the other hand nano-meter-scale particles. Two substrates technologies have been investigated: A1 2 O 3 DBC and Si 3 N 4 AMB. After the process optimization, tests vehicles have been assembled using both sintering processes, as well as a more classical high-temperature die attach technology: AuGe soldering. Multiple analyses have been performed, such as thermal resistance measurement, shear tests and micro-sections to follow the evolution of the joint during thermal cycling and high-temperature storage ageing.

Research paper thumbnail of Bonding strength of multiple SiC die attachment prepared by sintering of Ag nanoparticles

Journal of Materials Processing Technology, 2015

3 mm × 3 mm dummy SiC dies with 100\200\200 nm thick Ti\W\Au metallization have simultaneously be... more 3 mm × 3 mm dummy SiC dies with 100\200\200 nm thick Ti\W\Au metallization have simultaneously been attached using sintering of Ag nanoparticle paste on AlN-based direct bonded copper substrates with 5\0.1 m thick NiP\Au finish. The effect of preparation and sintering parameters including time of drying the printed paste, sintering temperature and time, and pressure, on the average shear strength for multiple die attachments was investigated. The surfaces of the die attachments after the shear tests were observed and the individual shear strength values correlated with the "apparent" porosity and thicknesses of the corresponding die attachments (sintered layer). The results obtained are further discussed and compared with typical data reported in existing literature. Main conclusions include: (i) the present shear strength values and their variations are comparable with those reported for single die attachment samples, (ii) the effects of sintering parameters can be ascribed to the effectiveness of the organic content burnout and appropriate rate of growth and coalescence of the Ag nanoparticles during the sintering process, and (iii) thickness values of the sintered Ag die attachments may be taken as nondestructive measurements to monitor/evaluate the quality of die attachment during power electronic module manufacturing/assembly process.

Research paper thumbnail of Die attach using silver sintering practical implementation and analysis

ABSTRACT. Silver sintering is a promising alternative to high melting point (HMP) solders which c... more ABSTRACT. Silver sintering is a promising alternative to high melting point (HMP) solders which contain lead. Indeed, it offers better thermal and electrical properties, and can operate at higher temperature. Currently, several implementations of this technique are available, based on various silver particles sizes and sintering additives. This paper presents a review of the different implementations, and gives practical details about one of them, based on silver nanoparticles. One specific aspect is highlighted: the metal finish of the DBC substrate. It has a major impact on the quality of the sintered joint: with some finishes, the adhesion is excellent (more than 50 MPa), while it is poor with some others (lower than 10 MPa). RÉSUMÉ. Le frittage d’argent est un candidat prometteur pour remplacer les brasures haute température au plomb. Il offre en effet de meilleures performances thermiques, électriques et fonctionne à plus haute température. Actuellement, plusieurs solutions exi...

Research paper thumbnail of Report de puce par frittage d'argent - mise en oeuvre et analyse

Le frittage d'argent est un candidat prometteur pour remplacer les brasures haute temperature... more Le frittage d'argent est un candidat prometteur pour remplacer les brasures haute temperature au plomb. Il offre en effet de meilleures performances thermiques, electriques, fonctionne a plus haute temperature. Plusieurs solutions existent actuellement, basee sur des particules d'argent de tailles differentes et l'ajout d'additifs de frittage. Ces solutions different par leur procedes de mise en oeuvre. Cet article presente un etat de l'art des differentes techniques, puis detaille la mise en oeuvre de l'une d'entre elles, basee sur des nanoparticules. Un point particulier est mis en evidence : la finition metallique des substrats DBC. Cette finition a un effet majeur sur la qualite du joint fritte, en particulier avec une finition "Ni-Au" : dans certains cas, l'attache est excellente (tenue uperieure a 50 MPa), alors que dans d'autres, elle est inferieure a 10 MPa.

Research paper thumbnail of Evaluation of printed-circuit boards materials for high temperature operation

Journal of microelectronics and electronic packaging, 2017

This article presents the long term (1000 h) behaviour of two printed-circuit board materials (Pa... more This article presents the long term (1000 h) behaviour of two printed-circuit board materials (Panasonic R1755V, a high-TG glass-epoxy composite and Arlon 85N, a polyimide-based laminate) stored at high temperature (190 °C). Tests are performed in air and in nitrogen atmospheres. Electrical and physical measurements are performed regularly (once per week). Almost no degradation is observed for both materials, when stored in nitrogen. On the contrary, the board stored in air show the consequences of ageing. This is especially true for the glass-epoxy material, which becomes unusable after 2 weeks, because of large swelling.

Research paper thumbnail of High temperature ageing of microelectronics assemblies with SAC solder joints

Microelectronics Reliability, Sep 1, 2017

In some applications, electronic systems are expected to operate at high ambient temperature (e.g... more In some applications, electronic systems are expected to operate at high ambient temperature (e.g. 150°C). In this paper, we investigate the failure mechanism and microstructure evolution of solder-free (SAC) solder joints at a maximum temperature of 175°C. It is found that no new failure mechanisms are triggered, and that ageing tests for solder can be accelerated at 175°C. In particular, the growth rate of the interfacial intermetallic compound (IMC) is found to be consistent with that observed at lower temperatures.

Research paper thumbnail of Contribution à l’étude des assemblages et connexions nécessaires à la réalisation d’un module de puissance haute température à base de jfet en carbure de silicium (SiC)

Http Www Theses Fr, Jun 25, 2013

Research paper thumbnail of Identification and analysis of power substrates degradations subjected to severe aging tests

Microelectronics Reliability, 2015

Si 3 N 4 substrate Severe aging cycles Severe thermal cycles [−55°C/+245°C] have highlighted degr... more Si 3 N 4 substrate Severe aging cycles Severe thermal cycles [−55°C/+245°C] have highlighted degradations in Active Metal Brazing Si 3 N 4 power substrates with copper metallization, nickel-plated and gold finish. After 1000 thermal cycles, the metallization patterns of the top side were imprinted on the rear one due to microcracking of the rear surface metallization and the surface roughness modification. This phenomenon was not observed in less severe thermal cycles such as [-40°C/+150°C]. This study focuses on the causes of this degradation appearance and on issues to prevent such phenomenon. First, the power electronics context is presented to justify the severe stresses applied to high temperature power modules and then induced degradations were described and analyzed. The choice was to perform a protocol of aging process by finite element simulations in order to have a better understanding on the propagation of mechanical stresses in the substrate which is the origin of these degradations. Indeed, this phenomenon could be reproduced by thermomechanical simulations. To propose solutions for these metallization reconstructions, the effect of the copper metallization thickness, the coefficient of thermal expansion of this layer, the substrate warpage and the size of metallization bonding tracks were assessed. The objective is to offer technological choices in terms of geometry of metallization track bonding (minimal etching or traditional engraving) and choices of materials used in power substrates in order to avoid these degradations in extreme environment conditions.

Research paper thumbnail of Lifetime of power electronics interconnections in accelerated test conditions: High temperature storage and thermal cycling

Microelectron. Reliab., 2017

We investigate the effect of three testing conditions (thermal shock, Rapid Temperature Change – ... more We investigate the effect of three testing conditions (thermal shock, Rapid Temperature Change – RTC – and high temperature storage) on the interconnects of a power electronic module. In particular, the mechanical strength of thick aluminium wirebonds is investigated and shows that while it is not affected by storage at 230 °C, it is much more sensitive to thermal cycling. Shock tests are found to be especially severe, despite having a smaller temperature swing than RTC. Regarding the die attach, no noticeable reduction in mechanical strength is found, regardless of the ageing conditions, and despite clear micro-structural evolutions.

Research paper thumbnail of Evaluation of silver-sintering die attach

Silver sintering die attach is a promising technology for high temperature power electronics pack... more Silver sintering die attach is a promising technology for high temperature power electronics packaging. In this paper, we evaluate its performances in terms of thermal resistance and high temperature stability. The thermal resistance is measured on test vehicles assembled under different conditions, using silver pastes from NBETech and Heraeus, with different process parameters. The stability test is performed by storing samples at an elevated temperature (300°C) in air, with a strong voltage bias (1100 V) for several hours.

Research paper thumbnail of Study of die attach technologies for high temperature power electronics: Silver sintering and gold–germanium alloy

Microelectronics Reliability, 2013

Silver sintering joints and AuGe soldering are promising technologies for high temperature (>200°... more Silver sintering joints and AuGe soldering are promising technologies for high temperature (>200°C ambient) power electronics packaging. This paper presents the implementation of two silver-sintering processes with the one hand micrometer-scale silver particles, and on the other hand nano-meter-scale particles. Two substrates technologies have been investigated: A1 2 O 3 DBC and Si 3 N 4 AMB. After the process optimization, tests vehicles have been assembled using both sintering processes, as well as a more classical high-temperature die attach technology: AuGe soldering. Multiple analyses have been performed, such as thermal resistance measurement, shear tests and micro-sections to follow the evolution of the joint during thermal cycling and high-temperature storage ageing.

Research paper thumbnail of Bonding strength of multiple SiC die attachment prepared by sintering of Ag nanoparticles

Journal of Materials Processing Technology, 2015

3 mm × 3 mm dummy SiC dies with 100\200\200 nm thick Ti\W\Au metallization have simultaneously be... more 3 mm × 3 mm dummy SiC dies with 100\200\200 nm thick Ti\W\Au metallization have simultaneously been attached using sintering of Ag nanoparticle paste on AlN-based direct bonded copper substrates with 5\0.1 m thick NiP\Au finish. The effect of preparation and sintering parameters including time of drying the printed paste, sintering temperature and time, and pressure, on the average shear strength for multiple die attachments was investigated. The surfaces of the die attachments after the shear tests were observed and the individual shear strength values correlated with the "apparent" porosity and thicknesses of the corresponding die attachments (sintered layer). The results obtained are further discussed and compared with typical data reported in existing literature. Main conclusions include: (i) the present shear strength values and their variations are comparable with those reported for single die attachment samples, (ii) the effects of sintering parameters can be ascribed to the effectiveness of the organic content burnout and appropriate rate of growth and coalescence of the Ag nanoparticles during the sintering process, and (iii) thickness values of the sintered Ag die attachments may be taken as nondestructive measurements to monitor/evaluate the quality of die attachment during power electronic module manufacturing/assembly process.

Research paper thumbnail of Die attach using silver sintering practical implementation and analysis

ABSTRACT. Silver sintering is a promising alternative to high melting point (HMP) solders which c... more ABSTRACT. Silver sintering is a promising alternative to high melting point (HMP) solders which contain lead. Indeed, it offers better thermal and electrical properties, and can operate at higher temperature. Currently, several implementations of this technique are available, based on various silver particles sizes and sintering additives. This paper presents a review of the different implementations, and gives practical details about one of them, based on silver nanoparticles. One specific aspect is highlighted: the metal finish of the DBC substrate. It has a major impact on the quality of the sintered joint: with some finishes, the adhesion is excellent (more than 50 MPa), while it is poor with some others (lower than 10 MPa). RÉSUMÉ. Le frittage d’argent est un candidat prometteur pour remplacer les brasures haute température au plomb. Il offre en effet de meilleures performances thermiques, électriques et fonctionne à plus haute température. Actuellement, plusieurs solutions exi...

Research paper thumbnail of Report de puce par frittage d'argent - mise en oeuvre et analyse

Le frittage d'argent est un candidat prometteur pour remplacer les brasures haute temperature... more Le frittage d'argent est un candidat prometteur pour remplacer les brasures haute temperature au plomb. Il offre en effet de meilleures performances thermiques, electriques, fonctionne a plus haute temperature. Plusieurs solutions existent actuellement, basee sur des particules d'argent de tailles differentes et l'ajout d'additifs de frittage. Ces solutions different par leur procedes de mise en oeuvre. Cet article presente un etat de l'art des differentes techniques, puis detaille la mise en oeuvre de l'une d'entre elles, basee sur des nanoparticules. Un point particulier est mis en evidence : la finition metallique des substrats DBC. Cette finition a un effet majeur sur la qualite du joint fritte, en particulier avec une finition "Ni-Au" : dans certains cas, l'attache est excellente (tenue uperieure a 50 MPa), alors que dans d'autres, elle est inferieure a 10 MPa.

Research paper thumbnail of Evaluation of printed-circuit boards materials for high temperature operation

Journal of microelectronics and electronic packaging, 2017

This article presents the long term (1000 h) behaviour of two printed-circuit board materials (Pa... more This article presents the long term (1000 h) behaviour of two printed-circuit board materials (Panasonic R1755V, a high-TG glass-epoxy composite and Arlon 85N, a polyimide-based laminate) stored at high temperature (190 °C). Tests are performed in air and in nitrogen atmospheres. Electrical and physical measurements are performed regularly (once per week). Almost no degradation is observed for both materials, when stored in nitrogen. On the contrary, the board stored in air show the consequences of ageing. This is especially true for the glass-epoxy material, which becomes unusable after 2 weeks, because of large swelling.

Research paper thumbnail of High temperature ageing of microelectronics assemblies with SAC solder joints

Microelectronics Reliability, Sep 1, 2017

In some applications, electronic systems are expected to operate at high ambient temperature (e.g... more In some applications, electronic systems are expected to operate at high ambient temperature (e.g. 150°C). In this paper, we investigate the failure mechanism and microstructure evolution of solder-free (SAC) solder joints at a maximum temperature of 175°C. It is found that no new failure mechanisms are triggered, and that ageing tests for solder can be accelerated at 175°C. In particular, the growth rate of the interfacial intermetallic compound (IMC) is found to be consistent with that observed at lower temperatures.

Research paper thumbnail of Contribution à l’étude des assemblages et connexions nécessaires à la réalisation d’un module de puissance haute température à base de jfet en carbure de silicium (SiC)

Http Www Theses Fr, Jun 25, 2013

Research paper thumbnail of Identification and analysis of power substrates degradations subjected to severe aging tests

Microelectronics Reliability, 2015

Si 3 N 4 substrate Severe aging cycles Severe thermal cycles [−55°C/+245°C] have highlighted degr... more Si 3 N 4 substrate Severe aging cycles Severe thermal cycles [−55°C/+245°C] have highlighted degradations in Active Metal Brazing Si 3 N 4 power substrates with copper metallization, nickel-plated and gold finish. After 1000 thermal cycles, the metallization patterns of the top side were imprinted on the rear one due to microcracking of the rear surface metallization and the surface roughness modification. This phenomenon was not observed in less severe thermal cycles such as [-40°C/+150°C]. This study focuses on the causes of this degradation appearance and on issues to prevent such phenomenon. First, the power electronics context is presented to justify the severe stresses applied to high temperature power modules and then induced degradations were described and analyzed. The choice was to perform a protocol of aging process by finite element simulations in order to have a better understanding on the propagation of mechanical stresses in the substrate which is the origin of these degradations. Indeed, this phenomenon could be reproduced by thermomechanical simulations. To propose solutions for these metallization reconstructions, the effect of the copper metallization thickness, the coefficient of thermal expansion of this layer, the substrate warpage and the size of metallization bonding tracks were assessed. The objective is to offer technological choices in terms of geometry of metallization track bonding (minimal etching or traditional engraving) and choices of materials used in power substrates in order to avoid these degradations in extreme environment conditions.

Research paper thumbnail of Lifetime of power electronics interconnections in accelerated test conditions: High temperature storage and thermal cycling

Microelectron. Reliab., 2017

We investigate the effect of three testing conditions (thermal shock, Rapid Temperature Change – ... more We investigate the effect of three testing conditions (thermal shock, Rapid Temperature Change – RTC – and high temperature storage) on the interconnects of a power electronic module. In particular, the mechanical strength of thick aluminium wirebonds is investigated and shows that while it is not affected by storage at 230 °C, it is much more sensitive to thermal cycling. Shock tests are found to be especially severe, despite having a smaller temperature swing than RTC. Regarding the die attach, no noticeable reduction in mechanical strength is found, regardless of the ageing conditions, and despite clear micro-structural evolutions.